Global Patent Index - EP 0915348 A3

EP 0915348 A3 2001-12-12 - Ground fault detection and protection method for a variable speed ac electric motor

Title (en)

Ground fault detection and protection method for a variable speed ac electric motor

Title (de)

Erdschlussüberwachungs- und Schutzverfahren für einen Wechselstrommotor mit veränderlicher Geschwindigkeit

Title (fr)

Système de détection et de protection de défaut d'isolement à terre d'un moteur électrique à courant alternatif et vitesse variable

Publication

EP 0915348 A3 (EN)

Application

EP 98309056 A

Priority

US 96628997 A

Abstract (en)

[origin: EP0915348A2] A method and apparatus for detecting the presence of a ground leakage path (39) in an electric motor system including an alternating current (ac) electric motor (40) coupled for receiving electric power from a switching inverter (27) of the type having, for each phase of the motor, a pair of serially connected electronic switching devices connected between relatively positive and negative direct current (dc) voltage buses (24,25) with the switching devices being alternately gated into and out of conduction for providing switched electric power to the motor. The inverter includes a current detector (29) for detecting current in the relatively negative voltage bus. The method comprises initially applying a gating pulse each time the motor is energized to the switching device (34, 36, 38) of each phase connected to the negative voltage bus and identifying a ground leakage path when such gating pulse produces current at the current detector. Preferably, the first gating pulse is of very short time duration and the process of applying gating pulses is repeated for each of a plurality of continuously increasing pulse widths until a selected maximum width is attained without generating current. Thereafter, the motor is started in a conventional manner. <IMAGE>

IPC 1-7 (main, further and additional classification)

G01R 31/02; G01R 31/34

IPC 8 full level (invention and additional information)

G01R 31/02 (2006.01); F04D 15/00 (2006.01); G01R 31/327 (2006.01); G01R 31/333 (2006.01); G01R 31/34 (2006.01); H02M 7/529 (2006.01); H02P 23/00 (2006.01); H02P 23/08 (2006.01); H02P 27/06 (2006.01); H02P 27/08 (2006.01)

CPC (invention and additional information)

G01R 31/025 (2013.01); F04D 15/0066 (2013.01); G01R 31/343 (2013.01); H02P 23/0077 (2013.01); H02P 23/08 (2013.01); H02P 27/08 (2013.01); H02H 7/0833 (2013.01); H02H 11/005 (2013.01)

Citation (search report)

Designated contracting state (EPC)

AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE

EPO simple patent family

EP 0915348 A2 19990512; EP 0915348 A3 20011212; EP 0915348 B1 20060104; DE 69833097 D1 20060330; DE 69833097 T2 20060831; JP 4012637 B2 20071121; JP H11235047 A 19990827; US 5945802 A 19990831

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